Cellulosic products containing thermoplastic microspheres are known in the art, cf. U.S. Pat. Nos. 3,556,934; 4,133,688, and 5,125,996; US Patent Appl'n Publ. No 2003/0152724; JP Laid Open Nos. 2002-254532 and 2003-105693; JP Patent No. 2689787; International Patent Appl'n Publ. Nos. WO 2001/54988, 2004/099499; 2004/113613 and 2006/068573; and Ö. Söderberg, “World Pulp & Paper Technology 1995/96, “The International Review for the Pulp & Paper Industry” p. 143-145.
Thermoplastic microspheres may be incorporated in cellulosic products to provide low density, high bulk paper and paperboard articles, e.g. insulated containers such as, for example, paper cups which can be used for serving hot and cold beverages. It has however been experienced that the porosity of such cellulosic products can be too high, thereby lowering the resistance to penetration of gases and aqueous liquids, specifically the edge wick resistance to penetration of aqueous liquids for sized cellulosic products containing thermoplastic microspheres.
It would be advantageous to be able to provide cellulosic products containing thermoplastic microspheres which exhibit improved properties, in particular improved porosity and edge wick resistance.